fix: keep plural fullform name with a comma decimal separator

[spokodev]

Bug

fullform picks the singular unit name for values it should pluralize whenever a comma is the decimal separator.

filesize(1500000, { fullform: true })                  // "1.5 megabytes"  (correct)
filesize(1500000, { fullform: true, separator: "," })  // "1,5 megabyte"   (wrong)
filesize(1500000, { fullform: true, locale: "de-DE" }) // "1,5 megabyte"   (wrong)

Any value in [1, 2) is affected, and those are extremely common ("1,2 GB", "1,5 MB").

Cause

decorateResult decides the singular/plural suffix by running parseFloat over the value after it has already been formatted into a string. parseFloat("1,5") stops at the comma and returns 1, so the val === 1 check treats 1.5 as exactly one and drops the plural s. Pluralization must depend on the magnitude, not on how the number is rendered.

Fix

Capture the numeric value before locale/separator formatting turns it into a string, and use that value for the plural decision. The precision string path ("1.2", period) still parses correctly, so existing behavior is unchanged.

Adds a regression test.

[augmentcode]

🤖 Augment PR Summary

Summary: Fixes incorrect singular fullform unit names when decimal commas are used via separator: "," or locale formatting.

Changes:

• Determines singular/plural based on the numeric value before locale/separator rendering
• Adds regression tests covering comma separators and de-DE locale output

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[augmentcode]

Review completed. 1 suggestion posted.

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[augmentcode]

numericValue is captured before applyNumberFormatting, but applyNumberFormatting can round via localeOptions (e.g., maximumFractionDigits) or the pad/round path. That can produce outputs like "1 …bytes" while numericValue is still slightly above/below 1, leading to a pluralization mismatch with the rendered value.

Severity: medium

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